Slough House is back in trouble — although that’s hardly anything new.
Apple TV has released the official trailer for Slow Horses Season 6, with Gary Oldman returning as Jackson Lamb as the dysfunctional MI5 team finds itself caught in another dangerous game of espionage, retaliation and revenge.
The six-episode season premieres Wednesday, September 16, 2026, with one episode, followed by new episodes every Wednesday through October 21.
Season 6 adapts Mick Herron’s Joe Country and Slough House, the sixth and seventh novels in his acclaimed Slough House book series.
This time, however, the Slow Horses aren’t simply stumbling into somebody else’s conspiracy.
They’re on the run.
The Slow Horses Are on the Run in Season 6
Season 6 finds Diana Taverner, played by Kristin Scott Thomas, embroiling the members of Slough House in what Apple describes as a fatally high-stakes game of retaliation and revenge.
That puts Jackson Lamb and his perpetually dysfunctional collection of MI5 castoffs in an unusually precarious position — even by Slough House standards.
Oldman returns alongside Jack Lowden as River Cartwright, Saskia Reeves as Catherine Standish, Christopher Chungas Roddy Ho, Aimee-Ffion Edwards as Shirley Dander and Tom Brooke as J.K. Coe.
The ensemble also includes Rosalind Eleazar, Joanna Scanlan, Samuel West, Ruth Bradley, Jonathan Pryce and Hugo Weaving.
BAFTA Award winner Lenny Rush joins the cast for Season 6.
Olivia Cooke Returns as Sid Baker
Season 6 will also welcome back a familiar face from the earliest days of Slow Horses.
Olivia Cooke will reprise her role as Sidonie “Sid” Baker, who was introduced alongside River as a member of Slough House during the show’s first season.
Her return adds another intriguing wrinkle to a season already pulling together characters and storylines from across Mick Herron’s Slough House novels.
With Jackson Lamb’s team on the run and Taverner at the center of the trouble, Sid’s reappearance should give longtime viewers another reason to pay particularly close attention to where Season 6 is headed.
Watch the Slow Horses Season 6 Trailer
Watch the official trailer for Slow Horses Season 6 below.
When Does Slow Horses Season 6 Premiere?
Slow Horses Season 6 premieres Wednesday, September 16, 2026, on Apple TV.
The six-episode season will debut with one episode, followed by a new episode every Wednesday through the finale on October 21.
All five previous seasons of Slow Horses are currently streaming on Apple TV.
Slow Horses Season 6 Cast
Gary Oldman, Kristin Scott Thomas, Jack Lowden, Saskia Reeves, Christopher Chung, Aimee-Ffion Edwards, Rosalind Eleazar, Joanna Scanlan, Samuel West, Ruth Bradley, Tom Brooke, Jonathan Pryce, Hugo Weaving, Lenny Rush and Olivia Cooke.
Season 6 is adapted for television by Gaby Chiappe, with Adam Randall returning to direct.
The series is produced for Apple TV by See-Saw Films. Jamie Laurenson, Hakan Kousetta, Julian Stevens, Iain Canning, Emile Sherman, Adam Randall, Gail Mutrux, Douglas Urbanski and Gary Oldman serve as executive producers.
Complete Slow Horses Coverage
Follow Seat42F for more Slow Horses news and coverage, including trailers, episode previews, photos, reviews and updates throughout Season 6.
Thomas Miller is the founder and Editor-in-Chief of Seat42F, covering television, movies and streaming entertainment. He launched Seat42F in 2007 and has spent nearly two decades covering the entertainment industry.
